use crate::vertex::MeshVertex;
use crate::fullscreen_quad::FullscreenVertex;
use crate::gpu::DEPTH_FORMAT;
use crate::gbuffer::{
    GBUFFER_POSITION_FORMAT, GBUFFER_NORMAL_FORMAT, GBUFFER_ALBEDO_FORMAT, GBUFFER_MATERIAL_FORMAT,
};
use crate::light::CameraUniform;

/// Bind group layout for the G-Buffer pass camera uniform (dynamic offset, group 0).
pub fn gbuffer_camera_bind_group_layout(device: &wgpu::Device) -> wgpu::BindGroupLayout {
    device.create_bind_group_layout(&wgpu::BindGroupLayoutDescriptor {
        label: Some("GBuffer Camera Bind Group Layout"),
        entries: &[
            wgpu::BindGroupLayoutEntry {
                binding: 0,
                visibility: wgpu::ShaderStages::VERTEX | wgpu::ShaderStages::FRAGMENT,
                ty: wgpu::BindingType::Buffer {
                    ty: wgpu::BufferBindingType::Uniform,
                    has_dynamic_offset: true,
                    min_binding_size: wgpu::BufferSize::new(
                        std::mem::size_of::<CameraUniform>() as u64,
                    ),
                },
                count: None,
            },
        ],
    })
}

/// Create the G-Buffer geometry pass render pipeline.
pub fn create_gbuffer_pipeline(
    device: &wgpu::Device,
    camera_layout: &wgpu::BindGroupLayout,
    texture_layout: &wgpu::BindGroupLayout,
    material_layout: &wgpu::BindGroupLayout,
) -> wgpu::RenderPipeline {
    let shader = device.create_shader_module(wgpu::ShaderModuleDescriptor {
        label: Some("GBuffer Shader"),
        source: wgpu::ShaderSource::Wgsl(include_str!("deferred_gbuffer.wgsl").into()),
    });

    let layout = device.create_pipeline_layout(&wgpu::PipelineLayoutDescriptor {
        label: Some("GBuffer Pipeline Layout"),
        bind_group_layouts: &[camera_layout, texture_layout, material_layout],
        immediate_size: 0,
    });

    device.create_render_pipeline(&wgpu::RenderPipelineDescriptor {
        label: Some("GBuffer Pipeline"),
        layout: Some(&layout),
        vertex: wgpu::VertexState {
            module: &shader,
            entry_point: Some("vs_main"),
            buffers: &[MeshVertex::LAYOUT],
            compilation_options: wgpu::PipelineCompilationOptions::default(),
        },
        fragment: Some(wgpu::FragmentState {
            module: &shader,
            entry_point: Some("fs_main"),
            targets: &[
                Some(wgpu::ColorTargetState {
                    format: GBUFFER_POSITION_FORMAT,
                    blend: None,
                    write_mask: wgpu::ColorWrites::ALL,
                }),
                Some(wgpu::ColorTargetState {
                    format: GBUFFER_NORMAL_FORMAT,
                    blend: None,
                    write_mask: wgpu::ColorWrites::ALL,
                }),
                Some(wgpu::ColorTargetState {
                    format: GBUFFER_ALBEDO_FORMAT,
                    blend: None,
                    write_mask: wgpu::ColorWrites::ALL,
                }),
                Some(wgpu::ColorTargetState {
                    format: GBUFFER_MATERIAL_FORMAT,
                    blend: None,
                    write_mask: wgpu::ColorWrites::ALL,
                }),
            ],
            compilation_options: wgpu::PipelineCompilationOptions::default(),
        }),
        primitive: wgpu::PrimitiveState {
            topology: wgpu::PrimitiveTopology::TriangleList,
            strip_index_format: None,
            front_face: wgpu::FrontFace::Ccw,
            cull_mode: Some(wgpu::Face::Back),
            polygon_mode: wgpu::PolygonMode::Fill,
            unclipped_depth: false,
            conservative: false,
        },
        depth_stencil: Some(wgpu::DepthStencilState {
            format: DEPTH_FORMAT,
            depth_write_enabled: true,
            depth_compare: wgpu::CompareFunction::Less,
            stencil: wgpu::StencilState::default(),
            bias: wgpu::DepthBiasState::default(),
        }),
        multisample: wgpu::MultisampleState {
            count: 1,
            mask: !0,
            alpha_to_coverage_enabled: false,
        },
        multiview_mask: None,
        cache: None,
    })
}

/// Bind group layout for the lighting pass G-Buffer textures + sampler (group 0).
/// position is Float non-filterable; normal/albedo/material are filterable.
pub fn lighting_gbuffer_bind_group_layout(device: &wgpu::Device) -> wgpu::BindGroupLayout {
    device.create_bind_group_layout(&wgpu::BindGroupLayoutDescriptor {
        label: Some("Lighting GBuffer Bind Group Layout"),
        entries: &[
            // binding 0: position texture (Rgba32Float → non-filterable)
            wgpu::BindGroupLayoutEntry {
                binding: 0,
                visibility: wgpu::ShaderStages::FRAGMENT,
                ty: wgpu::BindingType::Texture {
                    sample_type: wgpu::TextureSampleType::Float { filterable: false },
                    view_dimension: wgpu::TextureViewDimension::D2,
                    multisampled: false,
                },
                count: None,
            },
            // binding 1: normal texture (filterable)
            wgpu::BindGroupLayoutEntry {
                binding: 1,
                visibility: wgpu::ShaderStages::FRAGMENT,
                ty: wgpu::BindingType::Texture {
                    sample_type: wgpu::TextureSampleType::Float { filterable: true },
                    view_dimension: wgpu::TextureViewDimension::D2,
                    multisampled: false,
                },
                count: None,
            },
            // binding 2: albedo texture (filterable)
            wgpu::BindGroupLayoutEntry {
                binding: 2,
                visibility: wgpu::ShaderStages::FRAGMENT,
                ty: wgpu::BindingType::Texture {
                    sample_type: wgpu::TextureSampleType::Float { filterable: true },
                    view_dimension: wgpu::TextureViewDimension::D2,
                    multisampled: false,
                },
                count: None,
            },
            // binding 3: material texture (filterable)
            wgpu::BindGroupLayoutEntry {
                binding: 3,
                visibility: wgpu::ShaderStages::FRAGMENT,
                ty: wgpu::BindingType::Texture {
                    sample_type: wgpu::TextureSampleType::Float { filterable: true },
                    view_dimension: wgpu::TextureViewDimension::D2,
                    multisampled: false,
                },
                count: None,
            },
            // binding 4: non-filtering sampler (required for non-filterable texture)
            wgpu::BindGroupLayoutEntry {
                binding: 4,
                visibility: wgpu::ShaderStages::FRAGMENT,
                ty: wgpu::BindingType::Sampler(wgpu::SamplerBindingType::NonFiltering),
                count: None,
            },
        ],
    })
}

/// Bind group layout for the lighting pass lights + camera position uniforms (group 1).
pub fn lighting_lights_bind_group_layout(device: &wgpu::Device) -> wgpu::BindGroupLayout {
    device.create_bind_group_layout(&wgpu::BindGroupLayoutDescriptor {
        label: Some("Lighting Lights Bind Group Layout"),
        entries: &[
            // binding 0: LightsUniform
            wgpu::BindGroupLayoutEntry {
                binding: 0,
                visibility: wgpu::ShaderStages::FRAGMENT,
                ty: wgpu::BindingType::Buffer {
                    ty: wgpu::BufferBindingType::Uniform,
                    has_dynamic_offset: false,
                    min_binding_size: None,
                },
                count: None,
            },
            // binding 1: CameraPositionUniform
            wgpu::BindGroupLayoutEntry {
                binding: 1,
                visibility: wgpu::ShaderStages::FRAGMENT,
                ty: wgpu::BindingType::Buffer {
                    ty: wgpu::BufferBindingType::Uniform,
                    has_dynamic_offset: false,
                    min_binding_size: None,
                },
                count: None,
            },
        ],
    })
}

/// Bind group layout for shadow map + BRDF LUT (group 2).
pub fn lighting_shadow_bind_group_layout(device: &wgpu::Device) -> wgpu::BindGroupLayout {
    device.create_bind_group_layout(&wgpu::BindGroupLayoutDescriptor {
        label: Some("Lighting Shadow Bind Group Layout"),
        entries: &[
            // binding 0: shadow depth texture
            wgpu::BindGroupLayoutEntry {
                binding: 0,
                visibility: wgpu::ShaderStages::FRAGMENT,
                ty: wgpu::BindingType::Texture {
                    sample_type: wgpu::TextureSampleType::Depth,
                    view_dimension: wgpu::TextureViewDimension::D2,
                    multisampled: false,
                },
                count: None,
            },
            // binding 1: comparison sampler
            wgpu::BindGroupLayoutEntry {
                binding: 1,
                visibility: wgpu::ShaderStages::FRAGMENT,
                ty: wgpu::BindingType::Sampler(wgpu::SamplerBindingType::Comparison),
                count: None,
            },
            // binding 2: ShadowUniform
            wgpu::BindGroupLayoutEntry {
                binding: 2,
                visibility: wgpu::ShaderStages::FRAGMENT,
                ty: wgpu::BindingType::Buffer {
                    ty: wgpu::BufferBindingType::Uniform,
                    has_dynamic_offset: false,
                    min_binding_size: None,
                },
                count: None,
            },
            // binding 3: BRDF LUT texture
            wgpu::BindGroupLayoutEntry {
                binding: 3,
                visibility: wgpu::ShaderStages::FRAGMENT,
                ty: wgpu::BindingType::Texture {
                    sample_type: wgpu::TextureSampleType::Float { filterable: true },
                    view_dimension: wgpu::TextureViewDimension::D2,
                    multisampled: false,
                },
                count: None,
            },
            // binding 4: filtering sampler for BRDF LUT
            wgpu::BindGroupLayoutEntry {
                binding: 4,
                visibility: wgpu::ShaderStages::FRAGMENT,
                ty: wgpu::BindingType::Sampler(wgpu::SamplerBindingType::Filtering),
                count: None,
            },
        ],
    })
}

/// Create the deferred lighting pass render pipeline.
pub fn create_lighting_pipeline(
    device: &wgpu::Device,
    surface_format: wgpu::TextureFormat,
    gbuffer_layout: &wgpu::BindGroupLayout,
    lights_layout: &wgpu::BindGroupLayout,
    shadow_layout: &wgpu::BindGroupLayout,
) -> wgpu::RenderPipeline {
    let shader = device.create_shader_module(wgpu::ShaderModuleDescriptor {
        label: Some("Deferred Lighting Shader"),
        source: wgpu::ShaderSource::Wgsl(include_str!("deferred_lighting.wgsl").into()),
    });

    let layout = device.create_pipeline_layout(&wgpu::PipelineLayoutDescriptor {
        label: Some("Deferred Lighting Pipeline Layout"),
        bind_group_layouts: &[gbuffer_layout, lights_layout, shadow_layout],
        immediate_size: 0,
    });

    device.create_render_pipeline(&wgpu::RenderPipelineDescriptor {
        label: Some("Deferred Lighting Pipeline"),
        layout: Some(&layout),
        vertex: wgpu::VertexState {
            module: &shader,
            entry_point: Some("vs_main"),
            buffers: &[FullscreenVertex::LAYOUT],
            compilation_options: wgpu::PipelineCompilationOptions::default(),
        },
        fragment: Some(wgpu::FragmentState {
            module: &shader,
            entry_point: Some("fs_main"),
            targets: &[Some(wgpu::ColorTargetState {
                format: surface_format,
                blend: Some(wgpu::BlendState::REPLACE),
                write_mask: wgpu::ColorWrites::ALL,
            })],
            compilation_options: wgpu::PipelineCompilationOptions::default(),
        }),
        primitive: wgpu::PrimitiveState {
            topology: wgpu::PrimitiveTopology::TriangleList,
            strip_index_format: None,
            front_face: wgpu::FrontFace::Ccw,
            cull_mode: None,
            polygon_mode: wgpu::PolygonMode::Fill,
            unclipped_depth: false,
            conservative: false,
        },
        depth_stencil: None,
        multisample: wgpu::MultisampleState {
            count: 1,
            mask: !0,
            alpha_to_coverage_enabled: false,
        },
        multiview_mask: None,
        cache: None,
    })
}